The brown catshark (Apristurus brunneus) is commonly found in the Pacific Ocean, ranging from the northern Pacific waters off the coast of British Columbia and south to the Baja California peninsula in Mexico. They may live as far south as Ecuador and Peru. Brown catsharks are deep-water sharks that live on the outer continental shelf and the upper slope. They have been known to live at depths ranging from 30 to 650 m and live on the bottom, usually in muddy or sandy areas. The brown catshark, when originally described, was called Catulus brunneus.